Computer systems are often interconnected via one or more networks. Such networks can include a router configured to transfer a packet from an ingress port of the router to an egress port of the router. The router can be configured to extract a packet's destination address and forward the packet to an egress port that is associated with the destination address. The router can include multiple ingress ports and egress ports. A router can include a structure such as a crossbar switch or a bus to forward packets between ports.
In general, computer systems and routers are discrete, physically separate components. However, computer systems and one or more routers can be combined on a single integrated circuit (IC), or for brevity, chip. For example, such a chip can be referred to as a network on a chip (NoC). A NoC can include multiple processing cores that communicate using one or more on-chip routers. The on-chip routers can route packets to and from processing cores on the same chip or other chips.